1. Field of the Invention
The present application relates to selective deposition of patterned thin films on substrates. Such films find use, for example, in integrated circuits.
2. Description of the Related Art
Atomic layer deposition (ALD) processes grow thin films through surface reactions between alternately supplied gaseous precursors. Examples of these types of processes are described in detail in U.S. Pat. Nos. 4,058,430 and 5,711,811. The films typically grow on a substrate surface layer by layer and the film thickness and composition can be controlled with atomic layer accuracy in the growth direction. The ALD technique allows for deposition of conformal and uniform films over large areas.
Film growth can also be controlled on the surface with selective deposition processes, such as selective-area ALD. Selective-area ALD is done typically so that the designated areas of the surface are passivated or protected against ALD precursors, in which case the film is deposited only on desired parts of the surface. This can be done using self-assembled monolayers (SAMs) that passivate the surface against ALD growth or by using polymer films that passivate or protect the surface against ALD growth.
Activation of a surface for deposition is a new approach to selective-area ALD. Contrary to surface passivation, ALD growth occurs on activated areas of the surface. This can be done by preparing a patterned catalytic layer that can be for example noble metal. The ALD film is then deposited only on the catalytic layer while rest of the substrate surface will remain free of an ALD film. So far selective-area ALD of platinum has been done using patterned platinum made by electron beam induced deposition as a catalytic layer. Mackus, A. J. M.; Mulders, J. J. L.; van de Sanden, M. C. M.; Kessels, W. M. M. J. Appl. Phys. 2010, 107, 116102. Sputtered palladium film has been used as nucleation layer for ALD copper films. Gupta, R.; Willis, B. G. Appl. Phys. Lett. 2007, 90, 253102 In this case the copper film was deposited only on palladium, not on SiO2. Ruthenium films have been deposited selectively by chemical vapor deposition on a copper surface while no growth occurred on dielectric. Yang, C.-.; McFeely, F. R.; Wang, P.-.; Chanda, K.; Edelstein, D. C. Electrochem. Solid. St. 2010, 13, D33-D35.
Microcontact printing is a known technique for depositing films on the surface of a substrate. Previously microcontact printing has been used for depositing patterned passivation layers (SAM's, Thiols, etc) on a substrate.